This invention relates to polyurethane foam and a method of manufacturing polyurethane foam.
Polyurethane foam is conventionally manufactured by reacting polyols with polyfunctional isocyanates in the presence of a small amount of water. Carbon, dioxide is generated in the reaction between isocyanate and water and acts as the primary blowing agent. Commonly a chlorofluoroalkane, usually trichlorofluoromethane (CFC-11) is added to the reaction mixture as an auxiliary blowing agent. Other auxiliary blowing agents such as methylene chloride and methylene chloride/chlorofluoroalkane blends may be used, but these blowing agents are difficult to handle due to their toxicity.
U.S. Pat. No. 4,076,644 (E. I. du Pont de Nemours and Company) discloses polyurethane foams prepared using 1,1 dichloro 2,2,2, trifluoroethane (CFC-123) as the auxiliary blowing agent. This blowing agent is less efficient than CFC11, so more of it is required to make foams of comparable density.